Thank you for sharing your experience with our product. Hope you will become one of our happy litespeed enterprise customers soon.
If you don't mind prompting a commercial product, please help us spread the words in the vBulletin community. Thanks!

i will tell the vB community about my experience, the only bad thing is they don't offer help to their customers tweaking the litespeed configuration because they don't know the litespeed yet. (they only help apache & lighttpd)

PHP and MySQL optimizations should apply to all setup no matter which server is used.
LSWS comes with pretty optimized default configuration, maybe only a few minor changes are required, we have it covered.